Carol Milford is the woman who can be called an ambitious feminist in the modern times - but in her times she is seen as extremely eccentric. She is beautiful, intelligent and educated, finishing her college with the sincere dream to change the world for good. She starts her career as a librarian at St. Paul’s and is extremely excited with her job that gives her access to almost unlimited knowledge. Her happiness continues until she falls in love with the rural doctor named Will Kennicott. Their interests and life goals are completely different, but the naive and enamored young woman believes that they will work the things out. They have a wonderful honeymoon in Colorado and then Will suggests that they shall move to his native town, Gopher Prairie, settled in the middle of nowhere with the population of three thousand people. The town is a huge disappointment for Carol: the Main Street of it has only a few buildings, no park, no entertainment at all, and the locals look to her like miserable conformists, unable to take their own fate into their hands and change their native town for good. Still, Carol is overly enthusiastic to help them turn Gopher Prairie into the beautiful rural utopia and show them how beautiful it can be while everyone cares.
But suddenly she realizes that all her dreams have crashed into a wall of social ignorance. Carol is too used to the fun, social life and the quick pace of the big city, but in Gopher Prairie everything is different. The people are much slower, more reserved and immersed into their work, preferring not to express their feelings and completely content with the life Carol finds unbearable and boring. The young woman tries her best to express her progressive views on culture, politics and social life, she even becomes the living example, throwing parties and trying to make the locals to have fun with her - simultaneously trying to persuade them to treat the farmers and laborers better, because they are people too, equally to them - but it ends up badly. Carol earns the reputation of the weird airhead, a socialist and - what is more important - an improper wife for such a promising and serious young man as Will. Her husband strictly lectures her constantly for being so egoistic, insensitive to the needs of the neighbors and for tarnishing the family reputation.
Still, Carol is too strong-willed and determined to just yield to conformity. She starts a drama club, trying to share her ideas in the more interactive form. Suddenly, this idea meets at least some response and the amateur actors start preparing the simple play “The Girl from Kankakee”. Everyone seems to enjoy the preparation (even despite Carol was aiming for Shakespeare and they chose a lame comedy), but the cast completely ruins even such a simple play with the horrible, horrible acting. Carol’s feeling of beauty is severely hurt, but what is more humiliating for her is that everyone considers their play a huge success.
She makes another attempt by creating a bridge club for the young married women, where they can rest from their chores and have intellectual conversations - but conversations turn out to be not-so-intellectual. She finds out that there is a barely alive literary society in the town called Thanatopsis Club - but the topics there are also mundane and dull. A librarian by choice, Carol decides to learn why - and after the talk with the local librarian she realizes that the books here are treated as property, not as the sources of joy and knowledge. The librarian just doesn’t want people to take them home because they can lose or tear them and don’t like them to read books in the library, because she wants the room and the books to be kept clean. This revelation shocks Carol so much that she seizes her activity for some time. Moreover, she realizes that the conservative society of Gopher Prairie isn’t so harmless as it seemed before - Carol learns about the fate of the man who was ostracized for the death of his wife and child, even though he wasn’t the murderer, moreover, he didn’t have anything to do with their death. His exile happened just because community said so.
Still, Carol manages to make some friends (or, rather, frenemies) in the town. One of them is Vida Sherwin, who possesses some personal traits similar to Carol’s. They are both married to the respected men of the town and they are both intelligent - though Vida is content with her quiet family life and is very conservative in comparison with more liberal Carol. When Vida’s husband returns from the army and opens a local shop named Bon Ton, Carol tries to befriend him too. Another person she can have a conversation with is Guy Pollock, a local lawyer, who she sees a good intellectual match for her. He encourages her to continue trying to improve the town, but Carol fails one time after another. Another (unwanted) acquaintance of Carol is Percy Bresnahan, a wealthy man who advances at Carol repeatedly and is constantly rejected by her.
Suddenly, Carol finds another fellow soul - Miles Bjornstam, a man who is also considered a weirdo among the locals. His quirk is simple: he believes in workers’ rights. Carol is incredibly encouraged to talk to anyone who shares her ideals, and is almost ready to fall in love with Miles, but everything changes when Bjornstam marries Carol’s own maid, a local simple girl named Bea Sorenson. For the sake of safety of his wife and the newborn son Miles rejects his ideas to conform and become a “respected man”, so that Bea and their children won’t get bullied and humiliated for marrying (and being born in the family of) the wrong man. This doesn’t help him though: soon both Bea and their son die of typhus. Miles, feeling heartbroken for he has lost both himself and his family, leaves Gopher Prairie forever. Carol lets him go, feeling like she has also lost the only dear person to her, the man who she could talk to about her real feelings.
Without Miles, Carol tries once again, with all her passion, to love her new town and to love her husband, the feelings to whom start to inevitably fade. At first, putting all her enthusiasm to the new goal, Carol succeeds, but soon her frustration and repressed feelings return back. Carol is just not ready to waste all her life in the boring mediocre town of Gopher Prairie without any perspectives and possibilities. She can’t change herself and she can’t change the surrounding reality, that only leads to more frustration.
Desperately trying to find in her soul at least some love to Will and failing again, Carol tries to make herself alive by starting an affair with the young and handsome tailor’s assistant named Erik Valbourg. Valbourg is a dreamer, just like she is and they spend a lot of time sharing their dreams with each other. But it is almost impossible to hide an affair in the town as small as Gopher Prairie and soon Will finds it out. To Carol’s surprise, nothing dreadful is happening - her husband just strictly puts a stop to it, warning Carol that life with Erik would be much worse, because he is a descendant of a poor immigrant family. Soon Carol sees another ominous warning: the townsfolk exiles the young woman Fern Mullins, whose only fault is her love to Cy Bogart, her student. Fern has to leave, humiliated and disgraced - and soon Erik follows her way, driven away by the locals. Embittered, Carol realizes that despite being a romantic dreamer Eric just lacked the strength and courage to fulfill any of his dreams. Carol wonders if she is as weak as he is.
It seems that she is right. While Carol was fighting her depression, Vida Sherwin seemed to borrow her ideas and adopted them, bringing them to life with her practical attitude. Vida isn’t interested in literary and drama clubs, but she manages to start building the new school in the town right behind Carol’s back. This is a huge achievement, it is much more than all that Carol did before. Moreover, Carol now sees that Gopher Prairie is actually capable of changing for good - it’s just Carol who doesn’t fit there and the sheer desire for changes is not enough to make them happen.
In the last desperate attempt to save her marriage, Carol asks her husband for a trip to California to renew their feelings. They depart with their son Hugh and generally are having a good time, but the trip only shows that their definition of “good time” differs drastically. They are just too different one from another, two separate people, not connected by either worldview or priorities - and their love has burnt out long ago. Carol feels so disgusted by the thought of returning to Gopher Prairie eventually, that she just takes her son and leaves Will to go to Washington D.C. and try to start her life anew. Finally, Carol feels free and realizes that she can live on her own, enjoying the life of the big city. But after several years in Washington D. C. she understands that being a single mother there also means the rejections of all the great plans and ideas and focusing on a humble career and ensuring the survival of the family. This is the final blow to her idealism.
Broken, Carol returns to Gopher Prairie and reconciles with her husband. To her surprise, Will accepts her like nothing happened and they just continue their life together as a family. Carol finally understands that the real issue and the source of her anger isn’t some of the people, but the overall injustice and ignorance of the world and society around her. She can only live her life, dreaming that when her daughter will grow up, the times will be more merciful to her.